MQOPEN option for alternative user authority

When you attempt to open an object using the MQOPEN call, the queue manager checks that we have the authority to open that object. If we are not authorized, the call fails.

However, server programs might want the queue manager to check the authorization of the user they are working for, rather than the server's own authorization. To do this, they must use the MQOO_ALTERNATE_USER_AUTHORITY option of the MQOPEN call, and specify the alternative user ID in the AlternateUserId field of the MQOD structure. Typically, the server would get the user ID from the context information in the message it is processing.